Troubleshooting And Quieting Noisy Window AC Units

If your idea of the perfect air conditioner is one that purrs like a kitten while keeping the air in your home cool and comfy, you may find the noise of your window air conditioner annoying. If the noise is causing you discomfort, and you aren't in position to replace it with a low-noise model, check for these common culprits.

Rattling

One of the most common complaints about air conditioner noise is rattling when the unit is running. The sound may be caused by vibrations inside the unit or by vibrations from the window where the unit is installed. Here's how to solve them.

• Rattles from Inside the Unit: A properly installed window air conditioner does not rattle during operation. If you hear rattles or vibrations coming from inside the unit, this is a signal that parts are loose or that gaskets are missing. Tighten any loose parts and replace gaskets to stop vibration inside the unit. If your unit was professionally installed, call you HVAC contractor to have it fixed.
• Rattles from Windows: If your AC unit does not fit snugly into the window it may cause vibrations that rattle the windows. The first step to correcting the problem is to secure the unit. Use a level to check that your AC is level. You can place shims beneath the unit to level and secure it or add weather stripping between the unit and the window frame to prevent the unit from vibrating. Check the panes in your windows and recaulk them to secure the panes so that they cannot rattle.

Outside Noise

Sometimes it isn't the window unit itself that causes the annoying noises that keep you awake at night. Sounds from the outside, such as traffic or noisy neighbors, can filter in around the unit. This is especially true if you use window guards to block spaces between the unit and the window frame. These are often lightweight plastic and don't do a good job of filtering out noise. Cut foam board insulation to fill in any areas around the unit to help block out noises from outside. It won't eliminate noise completely, but it will reduce it. If you don't like the look of foam board, cover it with decorative fabric.

Noisy Fan

Air conditioner fans should operate smoothly without excessive noise, but when the blades get dirty they may cause a racket. Dust and grime from the air can build up over time and cause the blades to become unbalanced. Clean the fan blades with a damp cloth to remove any dirt or dust and quiet the sound of the fan.

Serious Internal Noises

You may hear a variety of annoying sounds from your AC that signal it is time to get the unit serviced. Some common sounds and their causes are:

• Banging: Loud banging or clanking noises generally indicate that your compressor has a broken part or needs to be replaced.
• Hissing: Hissing sounds coming from your AC unit indicate a refrigerant leak.
• Clicking: Annoying clicking sounds generally indicate that the thermostat is failing.
• Humming: If your AC unit develops a humming sound this may indicate that the starting capacitor is bad or is ready to fail.

Normal Noises

Even a low-noise air conditioner will make some noise. Thunking or clunking from the compressor when the unit starts up and shuts off may be normal for your unit. Unless the noise gets louder or happens more frequently, it is probably normal for your model. Some people also find the sound of blowing air annoying, but this cannot be avoided. Try placing the unit farther from your sleeping area if it disturbs your sleep, or set the blower or fan setting on low to quiet the sound.

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